/* ----------------------------------------------------------------------
 * Project:      CMSIS DSP Library
 * Title:        arm_rms_f32.c
 * Description:  Root mean square value of the elements of a floating-point vector
 *
 * $Date:        18. March 2019
 * $Revision:    V1.6.0
 *
 * Target Processor: Cortex-M cores
 * -------------------------------------------------------------------- */
/*
 * Copyright (C) 2010-2019 ARM Limited or its affiliates. All rights reserved.
 *
 * SPDX-License-Identifier: Apache-2.0
 *
 * Licensed under the Apache License, Version 2.0 (the License); you may
 * not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an AS IS BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "arm_math.h"

/**
  @ingroup groupStats
 */

/**
  @defgroup RMS Root mean square (RMS)

  Calculates the Root Mean Square of the elements in the input vector.
  The underlying algorithm is used:

  <pre>
      Result = sqrt(((pSrc[0] * pSrc[0] + pSrc[1] * pSrc[1] + ... + pSrc[blockSize-1] * pSrc[blockSize-1]) / blockSize));
  </pre>

  There are separate functions for floating point, Q31, and Q15 data types.
 */

/**
  @addtogroup RMS
  @{
 */

/**
  @brief         Root Mean Square of the elements of a floating-point vector.
  @param[in]     pSrc       points to the input vector
  @param[in]     blockSize  number of samples in input vector
  @param[out]    pResult    root mean square value returned here
  @return        none
 */

#if defined(ARM_MATH_MVEF) && !defined(ARM_MATH_AUTOVECTORIZE)
void arm_rms_f32(
	const float32_t *pSrc,
	uint32_t blockSize,
	float32_t *pResult)
{
	float32_t pow = 0.0f;

	arm_power_f32(pSrc, blockSize, &pow);

	/* Compute Rms and store the result in the destination */
	arm_sqrt_f32(pow / (float32_t) blockSize, pResult);
}
#else
#if defined(ARM_MATH_NEON) && !defined(ARM_MATH_AUTOVECTORIZE)
void arm_rms_f32(
	const float32_t *pSrc,
	uint32_t blockSize,
	float32_t *pResult)
{
	float32_t sum = 0.0f;                          /* accumulator */
	float32_t in;                                  /* Temporary variable to store input value */
	uint32_t blkCnt;                               /* loop counter */

	float32x4_t sumV = vdupq_n_f32(0.0f);                          /* Temporary result storage */
	float32x2_t sumV2;
	float32x4_t inV;

	blkCnt = blockSize >> 2U;

	/* Compute 4 outputs at a time.
	 ** a second loop below computes the remaining 1 to 3 samples. */
	while (blkCnt > 0U) {
		/* C = A[0] * A[0] + A[1] * A[1] + A[2] * A[2] + ... + A[blockSize-1] * A[blockSize-1] */
		/* Compute Power and then store the result in a temporary variable, sum. */
		inV = vld1q_f32(pSrc);
		sumV = vmlaq_f32(sumV, inV, inV);
		pSrc += 4;

		/* Decrement the loop counter */
		blkCnt--;
	}

	sumV2 = vpadd_f32(vget_low_f32(sumV), vget_high_f32(sumV));
	sum = vget_lane_f32(sumV2, 0) + vget_lane_f32(sumV2, 1);

	/* If the blockSize is not a multiple of 4, compute any remaining output samples here.
	 ** No loop unrolling is used. */
	blkCnt = blockSize % 0x4U;

	while (blkCnt > 0U) {
		/* C = A[0] * A[0] + A[1] * A[1] + A[2] * A[2] + ... + A[blockSize-1] * A[blockSize-1] */
		/* compute power and then store the result in a temporary variable, sum. */
		in = *pSrc++;
		sum += in * in;

		/* Decrement the loop counter */
		blkCnt--;
	}

	/* Compute Rms and store the result in the destination */
	arm_sqrt_f32(sum / (float32_t) blockSize, pResult);
}
#else
void arm_rms_f32(
	const float32_t *pSrc,
	uint32_t blockSize,
	float32_t *pResult)
{
	uint32_t blkCnt;                               /* Loop counter */
	float32_t sum = 0.0f;                          /* Temporary result storage */
	float32_t in;                                  /* Temporary variable to store input value */

#if defined (ARM_MATH_LOOPUNROLL) && !defined(ARM_MATH_AUTOVECTORIZE)

	/* Loop unrolling: Compute 4 outputs at a time */
	blkCnt = blockSize >> 2U;

	while (blkCnt > 0U) {
		/* C = A[0] * A[0] + A[1] * A[1] + ... + A[blockSize-1] * A[blockSize-1] */

		in = *pSrc++;
		/* Compute sum of squares and store result in a temporary variable, sum. */
		sum += in * in;

		in = *pSrc++;
		sum += in * in;

		in = *pSrc++;
		sum += in * in;

		in = *pSrc++;
		sum += in * in;

		/* Decrement loop counter */
		blkCnt--;
	}

	/* Loop unrolling: Compute remaining outputs */
	blkCnt = blockSize % 0x4U;

#else

	/* Initialize blkCnt with number of samples */
	blkCnt = blockSize;

#endif /* #if defined (ARM_MATH_LOOPUNROLL) */

	while (blkCnt > 0U) {
		/* C = A[0] * A[0] + A[1] * A[1] + ... + A[blockSize-1] * A[blockSize-1] */

		in = *pSrc++;
		/* Compute sum of squares and store result in a temporary variable. */
		sum += (in * in);

		/* Decrement loop counter */
		blkCnt--;
	}

	/* Compute Rms and store result in destination */
	arm_sqrt_f32(sum / (float32_t) blockSize, pResult);
}
#endif /* #if defined(ARM_MATH_NEON) */
#endif /* defined(ARM_MATH_MVEF) && !defined(ARM_MATH_AUTOVECTORIZE) */

/**
  @} end of RMS group
 */
